Thread: D4 suspension

Why not drop the tyres to the LR recommended pressures? Its easy enough to pump them back up a bit if too soft. As little as 2 psi difference can make a significant difference in ride.

Are we talking 19"s? I think 40psi is just way too high for the fronts and a bit high for the rear too unless carrying a load.

As Graeme suggested try starting with the placard pressures and going up from there. I'm running 34 front & 38 rear unladen on the bitumen with my Zeons and the ride is excellent.

Cheers,
Jon

Definitely let the pressures down to manufacturers settings unless you have a bar and winch in which case inflate the front to around 35. Nearly all the tyre fitters i have used have told me and set tyres at over 40psi. I personally think it is potentially dangerous advice. I ( and other friends of mine) have had close calls with lack of grip associated with too high pressures. Also spoils the ride quality.
I have no idea why the fitters give this advice. Some say it gives better economy. No good if you can't stay on the road. I firmly believe that it contributes to our inflated (no pun intended!) accident rate in this country.
I know that while I lived in the UK tyre fitters always had a a table of all makes and models and their associated recommended tyre pressures. I'm not sure if this was a legal requirement or not but it meant that all vehicles left the workshop with the correct pressures. Here it seems that 45 psi is the default pressure.
As a side note I have noticed that since I fitted my winch and bar the ride especially at the front has degraded a little bit. Also I see no problem with radial tyres bagging a bit.

ok guys ......thanks for the advice ....i will take the pressures down to the levels reccomended on the door plates and see what that does

also ....does anyone know if airsuspension deteriorates over time .....or is it the shocks that absorb the bumps ....so what does the air suspension do ...does it help absorb road shocks or does it just keep the car level on the road

sorry these may seem silly questions .....but i have no mechanical knoweledge what so ever

Effectively, the air suspension is doing the same job as a coil spring. It uses the compression of air instead of the torsion in a steel wire to act as the springing medium.

In a suspension system, the spring (in this case the air bag) absorbs the bump and the shock absorber (or more correctly, damper) controls the movement.

The air suspension itself doesn't deteriorate. Essentially, as long as the bag hasn't split it is working. It can leak, but I don't think this is relevant to what you are experiencing. The shocks will of course deteriorate, as you have experienced. In the Disco, the shock and air bag are in one integral unit, similar in principle to a McPherson strut.

All a bit of a simplification, but hope it helps.

Cheers,
Jon

Originally Posted by jon3950

Effectively, the air suspension is doing the same job as a coil spring. It uses the compression of air instead of the torsion in a steel wire to act as the springing medium.

In a suspension system, the spring (in this case the air bag) absorbs the bump and the shock absorber (or more correctly, damper) controls the movement.

The air suspension itself doesn't deteriorate. Essentially, as long as the bag hasn't split it is working. It can leak, but I don't think this is relevant to what you are experiencing. The shocks will of course deteriorate, as you have experienced. In the Disco, the shock and air bag are in one integral unit, similar in principle to a McPherson strut.

All a bit of a simplification, but hope it helps.

Cheers,
Jon

Thanks Jon ......ok so if the shocks and bags are an integral unit ....does that mean that when the shocks were replaced I got new bags as well ........

..if the shocks (dampers) control the movement and the airbags (suspension) controlls the bumps ....then any bumps are to do with the airbags ......or the tyre pressures .................right .????......

This is starting to make sense to my unmechanical mind !!

You can change the dampers independently of the air-bags (although of course, you still have to remove the entire strut assembly and break them apart). Many people don't bother and just replace the whole assembly, but you don't have to.

Simplistically, the bags "absorb" the bumps, the dampers "dampen" any rebound/oscillations.

Cheers,

Gordon

Originally Posted by gghaggis

You can change the dampers independently of the air-bags (although of course, you still have to remove the entire strut assembly and break them apart). Many people don't bother and just replace the whole assembly, but you don't have to.

Simplistically, the bags "absorb" the bumps, the dampers "dampen" any rebound/oscillations.

Cheers,

Gordon

oK so if I'm getting bumps in the ride then its the air bags not the shocks (dampers ) that would be the reason

so do these airbags deteriorate with age or vigerous use (like a good run over corregations ) .......
I think only the shocks (dampers) were replaced ....not the bags .....could the bags have deteriorated and so the " bumps are getting bigger " (apologies to Elvis Costello !!)